Jet control devices and methods

ABSTRACT

Examples of a jet control device are described. The jet control device can comprise a jet deflecting member that is configured to intercept and/or collide with a high speed jet emerging from a jet formation location. The interaction of the jet deflecting member and the jet can cause the high speed jet to be dispersed into a plurality of jets with a number of flow directions which may be sideways to an initial direction of the high speed jet. In one embodiment the deflecting member can include a liquid guide formed by injecting a fluid out of an outlet nozzle so that the liquid guide extends longitudinally away from the outlet nozzle. In another embodiment the deflecting member can include an array of solid pellets injected through an outlet in a direction of the emerging high speed jet and configured to collide with the emerging jet thereby deflecting its initial direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase of International ApplicationNo. PCT/CA2013/050272, filed Apr. 4, 2013, which claims the benefitunder 35 U.S.C. §119(e) of U.S. Provisional Patent Application No.61/620,326, filed Apr. 4, 2012, entitled “JET CONTROL DEVICES ANDMETHODS,” each of which is hereby incorporated by reference herein inits entirety.

TECHNICAL FIELD

This disclosure relates generally to fluid jet control device and methodof its use and more particularly relates to a fluid jet control deviceused to eliminate, reduce and/or deflect a flow of a high velocity fluidjet emerging out of a jet formation location.

DETAILED DESCRIPTION OF EXAMPLES OF JET CONTROL DEVICES AND METHODS

Overview

In systems where fluids are used as a working medium, high velocityfluid jets can be generated. Generation of high velocity fluid jets mayprovide various disadvantages such as loss of energy, mass or momentumof the working medium. In addition, fluid jets can escape out of acontrolled space causing damage to equipment or surrounding systems. Forexample, in a plasma compressing system, a high velocity liquid jet canbe generated by the collapse of a cavity enveloping and compressing theplasma. Such high velocity liquid jet may escape the plasma compressionsystem and can enter into neighboring systems thereby causing damage tothe equipment or performance of such systems.

Accordingly, there is a need to control the intensity and/or directionof the high velocity fluid jets such that the fluid jet does not reach aselected location and cause damage at that location.

SUMMARY

According to one aspect of the invention, there is provided a jetcontrol device for disrupting or deflecting a fluid jet from reaching aselected location. The device comprises means for injecting a jetdeflector material into a space containing a jet formation location atwhich the fluid jet is formed. The means for injecting is incommunication with a jet deflector material source and has a dischargeend directed at the jet formation location and is configured to injectthe jet deflector material in such a manner that the fluid jet formingat the jet formation location is disrupted or deflected away from theselected location.

The jet deflector material can be in a liquid state, in which case themeans for injecting is a liquid injector comprising a liquid conduitwith an injection nozzle at the discharge end. The injecting means canfurther comprise a control valve for controlling the flow of the liquidjet deflector out of the nozzle and/or pressurization means coupled tothe conduit and configured to supply sufficient pressure to direct acontinuous stream of the liquid jet deflector material to the jetformation location, wherein the stream has a substantially uniformradius. The pressurization means can be a pump or a pressurized gassource.

Alternatively, the jet deflector can be in a solid state, in which casethe means for injecting can be an extruder comprising a die and a ramconfigured to extrude the jet deflector material out of the extruder inthe form of an elongated rod. The extruder can be further configured toextrude the jet deflector material in the form of an elongated rodhaving a length that extends continuously at least from the dischargeend of the extruder to the jet formation location.

Instead of a solid state elongated rod, the jet deflector can be in asolid state in the form of discrete pellets, in which case the means forinjecting is a pellet driver having a breach and a movable gate forcontrolling the injection of solid state jet deflector pellets at thejet formation location. The pellet driver can be a rail gun or acompressed gas gun. Each pellet can have a face surface with a concaveshape.

According to another aspect of the invention, there is provided a plasmacompressing system comprising a plasma generator, a plasma compressionchamber, a pressure wave generator, a cavity generating means, and a jetcontrol device. The plasma generator is configured to generate plasmaand has a discharge outlet for discharging the generated plasma. Theplasma compression chamber has an outside wall defining an inner cavityof the chamber and an opening; the inner cavity of the chamber ispartially filled with a liquid medium and the discharge outlet of theplasma generator is in fluid communication with the inner cavity of thecompression chamber via the opening such that the generated plasma canbe discharged into the plasma compression chamber. The pressure wavegenerator comprises a plurality of pistons arranged around the chamber,wherein the pistons are configured to generate a converging pressurewave into the liquid medium. The cavity generating means is configuredto generate an elongated empty cavity in the liquid medium; the cavityhas a first end and a second end, wherein the first end is aligned atleast partially with the discharge outlet of the plasma generator suchthat the plasma discharged by the plasma generator enters the elongatedcavity. When the converging pressure wave reaches an interface of thecavity, the cavity collapses thereby enveloping the plasma. The jetcontrol device comprises means for injecting a jet deflector material incommunication with a jet deflector material source and having adischarge end directed at a jet formation location in the cavity. Themeans for injecting is configured to inject the jet deflector materialinto the cavity such that a fluid jet formed at the jet formationlocation is disrupted or deflected away from the plasma generator.

The jet deflector material can be in a liquid state, in which case themeans for injecting is a liquid injector comprises a liquid conduit withan injection nozzle at the discharge end. The liquid injector canfurther comprise a control valve for controlling the flow of the liquidjet deflector out of the nozzle and/or pressurization means coupled tothe conduit and be configured to supply sufficient pressure to direct acontinuous stream of substantially uniform radius of the liquid jetdeflector material to the jet formation location. The pressurizationmeans can be a pump or a pressurized gas source.

Alternatively, the jet deflector can be in a solid state, in which casethe means for injecting can be an extruder comprising a die and a ramconfigured to extrude the jet deflector material out of the extruder inthe form of an elongated rod. The extruder can be further configured toextrude the jet deflector material in the form of an elongated rodhaving a length that extends at least from the discharge end of theextruder to the jet formation location.

Instead of a solid state elongated rod, the jet deflector can be in asolid state in the form of discrete pellets, in which case the means forinjecting is a pellet driver having a breach and a movable gate forcontrolling the injection of at least one solid state jet deflectorpellet at the jet formation location. The pellet driver can be a railgun or a compressed gas gun.

The elongated solid rod or continuous liquid stream of the jet deflectormaterial can have dimensions that cause the collapse of the cavity tooccur at a surface of the elongated solid rod or continuous liquidstream.

The plasma compressing system can further comprise a shield disposed invicinity of the opening of the plasma compression chamber, and having anannular configuration for inhibiting a blob of liquid medium fromescaping the plasma compression chamber and entering the plasmagenerator. More particularly, the shield can be a wall projectingdownwardly into the inner cavity of the chamber surrounding the opening.The shield can be a lip shaped constriction formed at an edge of theopening and projecting radially toward a center of the cavity.

The jet deflector material can have the same composition as the liquidmedium in which case the system further comprises a liquid mediumcollection tank in fluid communication with the chamber and a fluidconduit fluidly coupling the collection tank with the jet deflectormaterial source.

The plasma compressing system can further comprise a controllerprogrammed to control a timing of the injection of the at least onesolid state jet deflector pellet into the cavity such that the pellet isin proximity to the collapse point when the cavity collapses.Alternatively, the controller can be programmed to control a timing ofthe injection of the continuous liquid stream of jet deflector materialinto the cavity such that the cavity collapses at the surface of thecontinuous liquid stream.

According to another aspect of the invention, there is provided a methodfor protecting a plasma generator of a plasma compression system from afluid jet formed in a compression chamber of the plasma compressionsystem, comprising: directing a jet deflector material at a jetformation location at which the fluid jet is formed such that the fluidjet is disrupted or deflected away from the plasma generator. Thecompression chamber can contain a liquid medium in which case a cavityis generated in the liquid medium into which plasma is injected by theplasma generator, and the jet deflector material is directed into thecavity. A converging pressure wave can be generated into the liquidmedium causing an interface of the cavity to collapse when theconverging pressure wave reaches the interface; in this case, the jetdeflector material is injected such that the cavity collapses at thesurface of the jet deflector material.

The method can comprise maintaining a lower pressure inside thecompression chamber than at a jet control device containing the jetdeflector material, such that the jet deflector material is sucked intocompression chamber and is directed to the jet formation location.Alternatively or additionally, the jet deflector material can bedirected at the jet formation location by injecting the jet deflectormaterial under pressure into the cavity. Alternatively, or additionally,the jet control device containing the jet deflector material can belocated above and be in communication with the compression chamber suchthat the jet deflector material is directed at the jet formationlocation by gravity.

In addition to the aspects and embodiments described above, furtheraspects and embodiments will become apparent by reference to thedrawings and study of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Sizes and relative positions of elements in the drawings are notnecessarily drawn to scale. For example, the shapes of various elementsand angles are not drawn to scale, and some of these elements arearbitrarily enlarged and positioned to improve drawing legibility.

FIG. 1A is a schematic cross-sectional view of a jet control deviceconfigured to discharge a liquid jet deflector, according to onenon-limiting embodiment.

FIG. 1B is a schematic cross-sectional view of a jet control deviceconfigured to discharge a solid rod jet deflector, according to anothernon-limiting embodiment.

FIG. 2 is a schematic cross-sectional view of the embodiment of the jetcontrol device shown in FIG. 1A installed in a plasma compressionsystem.

FIG. 3 is a schematic cross-sectional view of a jet control deviceconfigured to discharge solid pelletized jet deflectors according toanother non-limiting embodiment, and installed in a plasma compressionsystem.

FIG. 4 is a vertical cross-sectional view of a computational model of aplasma compression chamber illustrating an example of a pressurewavefront at early stages of propagation and a cavity shape.

FIG. 5 is a cross-sectional view in a horizontal direction of thecomputational model of the plasma compression chamber of FIG. 4. Thelegend bar at the bottom of the figure shows fluid pressure in Pascals.

FIG. 6 is a partial view of a computational model of a plasmacompression chamber illustrating an example of a plurality of pistonsarranged around a chamber's wall and an example of a jet deflectorinserted centrally within a cavity.

FIG. 7 a is a partial cross-sectional view of a computational model of aplasma compression chamber illustrating an example of a central highspeed liquid jet and a liquid blob when a jet deflector is not presentin a vortex cavity. The legend bar at the right upper corner of thefigure shows volume fractions of a liquid and a gas.

FIG. 7 b is a partial cross-sectional view of a computational model of aplasma compression chamber illustrating an example of liquid jets and aliquid blob when a jet deflector is present in a cavity.

FIG. 8 a is a partial cross-sectional view of a computational model of aplasma compression chamber illustrating an example of a central highspeed jet velocity.

FIG. 8 b is a partial cross-sectional view of a computational model of aplasma compression chamber illustrating an example of a liquid blobvelocity.

FIG. 9 a is a partial cross-sectional view of a computational model of aplasma compression chamber illustrating an example of a central highspeed jet velocity when a jet deflector is not present in a cavity.

FIG. 9 b is a partial cross-sectional view of a computational model of aplasma compression chamber illustrating an example of a velocity ofemerging jets when a jet deflector is present in a cavity.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Formation of high speed fluid jets can be a natural consequence duringcavities' collapse and has been observed in the past, for example byEnriquez et al. in the work “Collapse of Nonaxisymmetric Cavities”,Phys. Fluids 22 (2010) 091104, where a high speed central liquid jet hasbeen produced when an air cavity formed by a collision of a solid bodywith a liquid reservoir collapses due to hydrostatic pressure. Formationof a high speed liquid jet can be a relevant factor to certainprototypes of a plasma compression system that are under construction atGeneral Fusion, Inc. (Burnaby, Canada). In some examples of the plasmacompression system, a cavity (e.g., a vortex cavity) can be created byspinning a liquid medium within a plasma compression chamber. Plasma canbe injected within the vortex cavity of the compression chamber througha plasma generator. A converging pressure wave can be created in theliquid medium by a plurality of pneumatic pistons that are timed toimpact an outer surface of the plasma compression chamber. Impact of thepistons generates a converging pressure wave that travels towards thecenter of the compression chamber. The converging pressure wave cancollapse the vortex cavity and can envelop the plasma therebycompressing it. The pressure wave induced collapse of the vortex cavitycan cause a formation of a central high speed liquid jet that canproject away from a collapse point, along the axis of the vortex. Inaddition, a “blob” of a liquid medium can be created when the pressurewave approaches a plasma generator's nozzle. As used herein, a liquidblob can include (but is not limited to) a mass of liquid that is formedwhen a pressure wavefront approaches the generator's nozzle. The liquidblob can flow much slower than the central jet and can drip into thenozzle of the plasma generator. The liquid blob can have the form of ablob (e.g., a relatively amorphous mass of liquid) or can have the formof a spray, one or more drops or droplets, and so forth. Examples of aliquid blob are illustrated in FIGS. 7 a, 7 b and 8 b. The central jetemitted from the collapse point and the blob of liquid medium may enterinto the plasma generator thereby contaminating a plasma propagationchannel or causing any other damage to the generator or any diagnosticsystem used in the compression chamber or the plasma generator.

Embodiments of the invention described herein relate to a fluid jetcontrol device 10 for directing a jet deflector material at a fluid jetformation location such that a fluid jet is prevented from forming atthe fluid jet formation location, or is deflected or otherwise preventedfrom reaching a selected location, such as the aforementioned plasmagenerator. The fluid jet control device comprises a jet deflectormaterial container and means for injecting the jet deflector material atthe fluid jet formation location. The jet deflector material can be thesame or different state and the same or different material compositionas the fluid jet. FIG. 1A to FIG. 1B illustrate two differentembodiments of the fluid jet control device, and FIGS. 2 to 9 relate toembodiments of the fluid jet control device installed in a plasmacompression system to prevent a liquid jet formed at a jet formationlocation inside a compression chamber of the system from reaching aplasma generator of the system 100 (i.e. the selected location).However, it is to be understood that the jet control device is notrestricted to only this application, and instead the jet control devicecan be used for eliminating, reducing and/or redirecting a high speedjet in any systems, devices or engines where jet control is desired.

In one embodiment and referring to FIG. 1A, a jet control device 10 isconfigured to direct a liquid state jet deflector material (“liquid jetdeflector”) 12 at a fluid jet 18 emerging from a jet formation location20. The jet deflector material can have the same material composition orhave a different composition than the fluid jet, and the fluid jet canbe a liquid or a gas. The jet deflector container is a liquid reservoir11, and the means of injecting is a liquid injector 14 having a liquidconduit 16 fluidly coupled at one end to the liquid reservoir 11 and adischarge nozzle 17 at an opposite end of the conduit 16. The liquidinjector 16 can further comprise a control valve (not shown) forcontrolling flow of the jet deflector liquid out of the liquid injector14.

In order for the liquid jet deflector 12 to be discharged from theliquid injector 14, a pressure differential can be provided between theliquid injector 14 and the environment containing the jet formationlocation 20; the pressure differential and amount of liquid jetdeflector 12 should be large enough to cause the liquid jet deflector 12to be injected (or sucked) into the environment at a mass flow rate thatis sufficient to disrupt the fluid jet 18 or at least deflect the fluidjet 18 away from a location to be protected (“selected location”).Selection of this pressure differential and amount of liquid jetdeflector 12 will depend on certain properties of the fluid jet, such asits density and flow rate. In one embodiment, the liquid injector 14comprises a pressurization means such as a pump (not shown) coupled tothe liquid conduit 16 and operable to pressurize the liquid jetdeflector 12 in the liquid conduit 16 to a sufficient pressure abovethat of the environment containing the jet formation location 20 toprovide the required pressure differential; in this case the liquid jetdeflector 12 would be injected under pressure into the environment. Inanother embodiment, the jet control device 10 can be operated in anenvironment containing the jet formation location 20 that is at asufficient pressure below that of the jet control device 10 to providethe required pressure differential (“negative pressure differential”);in this case the liquid jet deflector 12 would be sucked intoenvironment when the control valve is opened. In yet another embodiment,the jet control device 10 is provided with a pressurization means and isoperated in an environment having a lower pressure than the jet controldevice 10 such that a combination of the pressurization means and thelower pressure of the environment provides the required pressuredifferential.

In operation, the liquid jet deflector 12 is directed by the liquidinjector 14 at the jet formation location, where the liquid jetdeflector 12 collides with the fluid jet emerging from the jet formationlocation. When the fluid jet 18 collides with the deflector liquid 12the direction of the fluid jet can be offset from its initial direction,and the fluid jet can be redirected away to a direction different fromthe initial jet direction and away from the target location. At the sametime the velocity of the fluid jet can be decreased due to the collisionwith the deflector liquid 12. In addition, due to the collision betweenthe fluid jet 18 and the liquid jet deflector 12, the cohesive body ofthe high speed jet can be fragmented reducing the size of the jet. Asmaller jet is less likely to stay as a cohesive body and can furtherdisintegrate into a spray of jets thereby reducing the jet's effects onequipment and systems surrounding an area influenced by such high speedjet.

In another embodiment and referring to FIG. 1B, a jet control device 10is configured to direct a solid state jet deflector material 12 in theform of an elongated rod (“solid rod jet deflector”) at the fluid jet18. The means for injecting is an extruder 14 which extrudes the solidstate jet deflector material 12 in the form of an elongated rod. The jetdeflector container 11 can be configured to store jet deflectorfeedstock in a solid or liquid state. In the former case, the feedstockis in the form of solid blanks and the container 11 can be provided withconveyor means for conveying the blanks to the extruder 14. In thelatter case, the jet deflector container is liquid reservoir 11 and isfluidly coupled to the extruder 14 such that the feedstock is flowedinto the extruder 14 and solidified therein. The extruder 14 comprises adie 16 coupled to the jet defector container 11 at one end and alsocomprises extrusion nozzles 17 at an opposite discharge end. Theextruder 14 also comprises a ram (not shown) to force the feedstockthrough the die. The extruder 14 can employ a hot or warm extrusionprocess in which case the extruder 14 can further comprise a heaterthermally coupled to the die to heat the feedstock to a suitableextrusion temperature. The jet deflector material 12 can have the samematerial composition or have a different composition than the fluid jet18. For example, the jet deflector material can be a lead or lead andlithium mixture.

The extruder 14 is configured to extrude the solid jet deflector 12 asan elongated rod that is long enough to reach the jet formation locationwhile still being physically engaged with the extruder 14. The solid jetdeflector 12 can be extruded to meet the fluid jet 18 at the formationlocation 20 when the momentum of the fluid jet is still low; the solidjet deflector can be stationary or moving at the jet formation location20. The elongated rod 12 is dimensioned based on the parameters of thefluid jet 18 at the formation location 20.

The momentum of a fluid jet at the formation location can be calculatedas:P=υ×m

where υ is a speed of the fluid jet at the formation location (initialspeed) and m is a mass of the fluid jet at the formation location.

For example, when a fluid jet is composed of molten lead with a mass ofabout 0.04-0.1 kg and a jet speed at the formation location of about400-1500 m/s, the momentum of the fluid jet 18 at the formation location20 is about 20-160 kg m/s. It is expected that when the solid rod jetdeflector 12 is placed in a stationary position at the jet formationlocation 20, it will need to have dimensions of around 2-4 cm indiameter and around 1-10 m in length in order to deflect the directionof the fluid jet 18. If the elongated rod is injected with a speed ofabout 10 m/s the length of the rod can be in a range of about 0.1-3 mfor a rod with diameter of about 2-4 cm.

In another embodiment, the jet deflector can be in a solid state in aform of discrete pellets. The pellets can be injected using a pelletdriver having a breach and a movable gate for controlling the injectionof the jet deflector pellets to the jet formation location 20. Thepellet driver can be a rail gun or a compressed gas gun.

Referring now to FIG. 2, the jet control device (numbered 200) accordingto the embodiment shown in FIG. 1A is installed in a plasma compressionsystem 100 and operated to prevent liquid jets formed in a compressionchamber 120 of the system 100 from reaching a plasma generator 110 ofthe system 100, wherein the liquid jets are formed from the liquidmedium in the compression chamber 120. The jet control device 200 isconfigured to inject a stream of liquid jet deflector 210 into thecompression chamber 120. The compression chamber 120 can be partiallyfilled with the liquid medium in which an elongated empty cavity 140 canbe formed. Plasma 125 can be injected in the cavity 140 by the plasmagenerator 110. The plasma 125 can be magnetized toroidal plasma such as,e.g., a spheromak, a field-reversed configuration (FRC) of plasma or anyother compact toroid configuration or their combination or combinations.In one implementation any other gaseous medium can be injected into thecavity 140.

The compression chamber 120 comprises a wall 130 that defines an innercavity 132 of the compression chamber, an opening 185 through which theplasma 125 can be injected into the cavity 140 and a plurality ofpressure wave generators 160 arranged around the compression chamber120. The inner cavity 132 of the chamber 120 can be partially filledwith the liquid medium. The liquid medium can be a molten metal, such aslead, lithium, or sodium, or an alloy, combination, or mixture ofmetals. In one implementation, the elongated cavity 140 is formed byrotating the liquid medium contained within the compression chamber 120,and in particular, the compression chamber 120 comprises a vortexgenerator 150 for generating the elongated cavity 140. The vortexgenerator 150 includes an outlet conduit 152, a pump 154, and an inletconduit 156. In the illustrated example, the pump 154 is operable topump a portion of the liquid medium out of the chamber 120 through theoutlet conduit 152 located near a pole of the chamber 120, and isoperable to inject liquid medium into the chamber 120, tangentially nearan equator of the chamber 120, through the inlet conduit 156. In oneimplementation, the outlet 152 is spaced from the pole towards theequator of the chamber 120. In an alternative embodiment (not shown),more than one inlet 156 and/or outlet 152 can be used to circulate theliquid medium within the chamber 120. Flow of the liquid medium at asufficiently rapid rotational rate creates the cavity 140 that issubstantially free of the liquid medium.

Other means known in the art for generating the cavity 140 can be usedwithout departing from the scope of the invention. For example, in oneimplementation, the elongated cavity 140 can be formed, for example, byinjecting jet(s) of liquid medium from an annular nozzle formed at theopening 185 of the compression chamber 120, or by passing a shaped solidobject through the liquid medium at high speed, etc.

With respect to the embodiment shown in FIG. 2, the compression chamber120 has a spherical shape with the opening 185 formed at a pole of thechamber 120. However, this is for illustration purposes only and theplasma compression chamber 120 can have another shape (e.g. cylindrical,spherical, ellipse, conical or any other suitable shape or combinationthereof) and/or dimension without departing from the scope of theinvention.

The elongated cavity 140 has a first end that is at least partiallyaligned with the opening 185. The plasma generator 110 is configured togenerate and inject the plasma 125 into the cavity 140 through theopening 185. A second outlet end 190 of the plasma generator 110 isslightly inserted into the opening 185 to provide fluid communicationbetween the plasma generator 110 and compression chamber 120. In theillustrated embodiment, the chamber 120 has two annular openings 185 and185 a, located at each pole of the chamber 120. Optionally, the system100 can comprise a second plasma generator 110 a (shown only partiallyin FIG. 2), which is positioned diametrically opposite the first plasmagenerator 110. Each of the two openings 185, 185 a are in communicationwith the two separate plasma generators 110 and 110 a. Details regardingvarious embodiments of plasma generator 110, 110 a that can be used withthe system 100 are described in the commonly owned U.S. PatentApplication Publication No. 2006/0198483, U.S. Patent ApplicationPublication No. US2011/0026657 and U.S. Patent Application PublicationNo. US2011/002665, incorporated by reference herein in their entirety.

In one implementation, the elongated cavity 140 has a substantiallycylindrical shape and extends all the way through the chamber 120 fromone pole of the chamber 120 to the opposite pole. In anotherimplementation, the cavity 140 has a more conical shape which extendsthroughout the whole length of the chamber 120 (pole to pole) or onlypartway through the length of the chamber 120. The elongated cavity 140can be positioned substantially vertically or substantially horizontallyin the chamber 120 without departing from the scope of the invention. Atleast one end of the cavity 140 needs to be aligned with the opening 185and the second end 190 of the plasma generator so that the plasma 125(or any other gaseous medium) can be injected into the cavity 140.

The plurality of pressure wave generators 160 are configured to create apressure wave in the liquid medium contained within the chamber 120. Thepressure wave generators 160 are oriented radially, outwardly from thewall 130. The pressure wave generators 160 are operable to generate apressure wave in the liquid medium by impacting the wall 130 of thechamber 120. In one embodiment, the pressure wave generator 160 includesa hammer piston that is driven to impact the wall 130 of the chamber120. The kinetic energy due to the piston impact can cause a compressionwave in the wall 130 which travels through the wall and into the liquidmedium, thus generating the pressure wave in the liquid medium. Thegenerated pressure wave should propagate through the liquid medium andconverge toward the center of the chamber 120. In another embodiment, apressure wave generator 160 comprises a transducer that is securedwithin a corresponding opening in the wall 130 or otherwise coupled tothe wall 130. A pressure wave is generated by impacting the transducerwith a corresponding hammer piston. Details regarding variousembodiments of pressure wave generators 160 that may be used withvarious embodiments of the system 100 can be found in co-owned U.S.Patent Publication No. 2010/0163130 and International Patent Application(PCT) Publication No. WO 2012/113057, which are incorporated byreference herein in their entirety.

The number and position of the pressure wave generators can be selectedso that a pressure wave with desired shape and amplitude can begenerated in the liquid medium. For sake of clarity, FIG. 2 shows onlysome of the pressure wave generators 160.

Plasma is generated and accelerated by the plasma generator 110, (and110 a, if used) and is injected into the compression chamber 120 throughthe outlet end 190 and the opening 185. The outlet end 190 is alignedwith the opening 185 of the chamber 120. The generated convergingpressure wave can have a leading edge or wavefront 170. The convergingpressure wave can travel through the liquid medium and can strike acavity interface (liquid/gas interface). As a result, the interface canundergo rapid acceleration and can continue its movement towards acenter of the chamber 120, collapsing the cavity and compressing theplasma 125 within the converging cavity (see FIG. 3). Timing of theimpact and thus generation of the converging pressure wave can beprecisely controlled so that the plasma can be injected into the cavity140 before it collapses. The collapse of the cavity 140, induced by theconverging pressure wave, can trigger generation of a high speed centraljet of the liquid in the chamber 120 (not shown in FIG. 2, but shown as180 in FIG. 3). The liquid jet can have the form of a “spike” of liquiddirected centrally away from a collapse point. When the liquid jetemitted from the collapse point moves in a direction toward the plasmagenerator(s) 110, 110 a the liquid jet can enter and/or damage thegenerator(s) 110, 110 a or contaminate a plasma propagating channel 195in the generator(s) 110, 110 a.

In order to reduce the likelihood that the central jet enters the plasmagenerator 110, 110 a, the jet control device 200 is employed to disruptor deflect the liquid jet from reaching the plasma generator(s) 110, 110a. The jet control device 200 comprises a liquid injector that includesa liquid conduit 205 with an outlet nozzle 207. The jet control device200 can further comprise a control valve 208 configured to close andopen the outlet nozzle 207. The jet control device 200 is oriented suchthat a liquid jet deflector 210 can be injected from the jet controldevice 200 into the cavity 140 along its axis 250. A liquid storage tank220 is fluidly coupled to the conduit 205 and supplies the liquid jetdeflector to the conduit. The liquid storage tank 220 is placed within acentral part of the plasma generator 110. In one embodiment the storagetank 220 can be electrically insulated from the plasma generator 110.

The liquid jet deflector 210 in this embodiment has the same compositionas the liquid medium in the compression chamber 120 which may beadvantageous in view of the likely mixing of the liquid of the deflector210 and the liquid medium of the chamber 120. For example, the liquidjet deflector 210 and the liquid medium in the chamber is a moltenmetal, such as lead, lithium, or sodium. Alternatively, the liquid jetdeflector 210 can have a different composition from the liquid medium inthe chamber 120, provided the deflector 210 is in a liquid state underoperating conditions and a system for separating the different materialof the deflector 210 from the liquid medium in the chamber 120 isprovided (not shown).

The plasma compression chamber 120 is typically maintained at a pressurethat is lower than the pressure inside the plasma generator 110; as theliquid storage tank 220 is located in the plasma generator 110, anegative pressure differential would thus exist between the jet controldevice 200 and the cavity 140 containing the jet formation location.Also, the jet control device 200 is positioned above the cavity 140 suchthat the nozzle 207 is aimed downwards. Therefore, gravity and a suctionforce caused by the pressure differential will cause the liquid jetdeflector 210 to flow from the liquid storage tank 220 to the fluidconduit 205 and then out of the outlet nozzle 207 and into the cavity140 when the control valve 208 is opened. As will be described in moredetail below, the pressure differential between the jet control device200 and the cavity 140 can be configured to provide (with the assistanceof gravity) the liquid jet deflector 210 with a sufficient mass flowrate to disrupt or deflect a liquid jet from reaching the plasmagenerator(s)) 110, 110(a). Optionally, pressurization means such as apump or pressurized gas supply (neither shown) can be coupled to theconduit 205 to increase the pressure differential to the requireddegree.

To determine the pressure required to provide the required mass flowrate of the liquid jet deflector 210, certain operating parameters forthe liquid jet deflector 210 are defined. First, the liquid jetdeflector injection system 200 should inject enough liquid jet deflectormaterial into the cavity that a continuous stream of liquid extends fromthe nozzle 207 and into the cavity 140. Also, the radius of the liquidjet deflector 210 stream should be as uniform as possible along itslength and therefore the liquid jet deflector 210 can be injected withan initial velocity sufficient to prevent a narrowing of the liquid jetdeflector 210 as it flows down the cavity 140 due to the gravity. Fromthe energy balance is known that:V _(bottom) ² −V _(top) ²=2gH,where V_(top) and V_(bottom) are velocities of the liquid jet deflector210 at the top (in proximity to the control valve 208) and at the bottom(opposite end of the liquid jet deflector 210); g is acceleration due togravity and H is a length of the liquid jet deflector 210. For acompression chamber 120 with a height of about ˜3 m and a cavity 140extending from one pole of the chamber 120 to the other pole, the liquidjet deflector has a length of about 3 m (extending throughout the wholelength of the cavity 140). If we assume that the change in the velocityis for example less than 25% (V_(bottom)=1.25 V_(top)) than theinjection velocity is:

$V_{top} = {\sqrt{\frac{2{gH}}{1.25^{2} - 1}} \approx {10\mspace{14mu} m\text{/}s}}$

In order to achieve this injection velocity, the fluid has to beinjected under pressure

$P = {\frac{1}{2}\rho\;{V_{top}^{2}.}}$

For a molten lead deflector with density ρ=10000 kg/m³ and V_(top)=10m/s the pressure required to inject the liquid jet deflector 210 isabout P=500000 Pa≈5 Atm and can be provided by pressurization means suchas a compressed gas in the liquid tank 220 to push the molten metal downthe conduit 205 or by maintaining a pressure differential between thejet control device 200 and the cavity 140, or by both. This is forillustrative purposes only and liquid jet deflector 210 with higherinitial velocity can be injected without departing from the scope of theinvention, assuming that a deflector with more or less uniform radiusalong its length is provided. The radius of the liquid jet deflector 210(R_(deflector)) depends on the radius of the cavity 140 (R_(cavity)) andis a fraction of the radius of the cavity. For example, the radius ofthe liquid jet deflector 210 is around0.1Rcavity≦R_(deflector)≦0.2R_(cavity). The material composition of theliquid jet deflector 210 can be the same as the liquid medium in thecompression chamber 120. For example, for a cavity with a radius ofabout 20 cm the radius of the liquid jet deflector 210 is about 2-4 cm.

A liquid circulation assembly 230 can be used to recirculate the liquidfrom the collection tank 225 back into the storage tank 220 for reuse;this assembly 230 comprises a fluid conduit having an inlet fluidlycoupled to the collection tank 225 and an outlet coupled to the liquidstorage tank 220. When the deflector 210 is a continuous liquid columnflowing throughout the entire length of the vortex, the formation of thehigh speed liquid jet 180 can be prevented since the collapse of thecavity is not at a point but rather at a surface of the liquid jetdeflector 210. So, one or more jets that can be generated during thecollapse of the cavity 140 at the deflector's surface should be directedby the liquid jet deflector 210 into a main liquid body in the chamber120.

In one implementation, the liquid jet deflector 210 is injected into thecavity 140 in a controlled and timed manner. A controller (not shown) isprovided which is programmed to control an opening of the control valve208 and/or a generation of the pressure wave so that the liquid jetdeflector 210 can be injected and extended at least partially throughoutthe length of the cavity 140 when the plasma enters the cavity 140 sothat the collapse of the cavity can happen at the surface of the liquidjet deflector 210. The dimensions of the liquid jet deflector 210 canvary depending on the energy of the emerging jet. For example, thelength of the deflector 210 stream can be the same as the radius of thecompression chamber 120. In some implementations, the length of thedeflector 210 stream can be less or more than the radius of thecompression chamber 120.

As noted above, the liquid jet deflector 210 can be injected underpressure, using a pump or compressed gas to push the liquid jetdeflector 210 into the conduit 205 and out of the nozzle 207. Thepressure can be selected to cause the liquid jet deflector 205 to flowinto the cavity 140 and collide with a high speed liquid jet emerging atthe collapse point. For example, a liquid jet deflector 210 stream withradius of about 2-4 cm and a flow rate of about 10 m/s or more thatmeets a liquid jet at the collapse point or close to the collapse point(a jet momentum of about ˜20-160 kg m/s) can break up the cohesive bodyof the jet into smaller jets that can be redirected into the main bodyof liquid medium. The injection of the liquid jet deflector 210 and itsenergy (or pressure) can be synchronized with the cavity collapse insuch a way that the bulk of jet's energy is reduced and the jet isprevented from reaching the generator's outlet end 190.

In another embodiment a jet control device as shown in FIG. 1B can beinstalled in a plasma compression system 100 like the one shown in FIG.2 and operated to prevent liquid jets formed in a compression chamber120 of the system 100 from reaching a plasma generator 110 of the system100, wherein the liquid jets are formed from the liquid medium in thecompression chamber 120. The jet control device is configured to injecta continuous solid rod jet deflector 210 into the compression chamber120; the blanks contain enough feedstock material for the extruder 14 toform a solid rod with enough length to extend from the extrusion nozzle17 throughout the entire length of the cavity 140. In some modes ofoperations, the solid rod jet deflector 12 can be destroyed completelyor partially during the operation of the system 100. Hence, it can beadvantageous for the solid rod jet deflector 12 to be made of the samemetal as the liquid metal in the chamber 120. In such case, a new solidrod jet deflector 12 can be extruded by using some of the liquid metalin the chamber 120. The solid rod jet deflector 12 can have variousdifferent sizes and shapes depending on the size of the cavity 140and/or the size and the shape of the chamber 120. It can be dimensionedso that it does not interfere with the plasma entering the cavity. Forexample, the deflector can be cylindrically shaped with a diameter ofabout ⅕- 1/10 of a diameter of the cavity 140.

In an alternative implementation, a jet control device (not shown) isconfigured to inject both a solid rod jet deflector and a liquid streamjet deflector simultaneously. The jet control device is provided with anextruder like the embodiment shown in FIG. 1B, and also has a liquidinjector like the embodiment shown in FIG. 1A positioned beside theextruder, such that the liquid stream flows alongside the solid rod intothe cavity. Alternatively, the extruder is located coaxially and insidethe liquid injector, such that the liquid stream in injected around theperiphery of the solid rod and flows around the length of the rod intothe cavity. The composition of the liquid stream can be lithium and canform a thin layer of lithium over the solid rod jet deflector, which isexpected to present a low Z material at a plasma-facing surface and thusminimize radiation losses due to plasma contamination. Alternatively,both the solid and liquid jet deflectors can be made of a differentmaterial from the liquid medium, in which case the system is providedwith means for separating the material of the deflector 210 from theliquid medium. After separation, the liquid medium is returned into thecompression chamber 120 while the jet deflector material is returned tothe jet control device.

For plasma compression systems 100 using either the liquid jet controldevice 10 of FIG. 1A or the solid rod jet control device 10 or FIG. 1B,the interaction of the pressure wavefront and the outlet end 190 of thegenerator 110 can result in a blob of liquid medium forming near theoutlet 190. In order to inhibit or prevent such a liquid blob fromentering the plasma generator 110 (or the generator 110 a, if used) thejet control device 200 further comprises a shield 240, as can seen inFIG. 2. The shield 240 can prevent the blob of liquid medium fromentering the outlet end 190 of the generator 110. When a second plasmagenerator 110 a is used, the jet control device 200 comprises a secondshield 240 a, generally similar to the shield 240, which is located nearthe second plasma generator's 110 a outlet end.

In the embodiment shown in FIG. 2, the shield 240 is connected to thewall 130 in proximity to the annular opening 185; alternatively theshield 240 forms an integral part of the wall 130. In either case, theshield 240 for the downwardly facing plasma generator 110 is acylindrical body (e.g., a skirt) extending downwardly from an innersurface of the wall 130 (and extending upwardly for the upwardly facingplasma generator 110 a). The shield 240, 240 a is dimensioned so that itcan prevent the liquid blob from entering the plasma generator(s) 110,110 a. For example, the length of the shield 240, 240 a can be around1/10 to 1/7 of the height of the plasma compression chamber 120 (0.2-0.4m for the plasma compression system 100 shown in FIG. 2 having a chamber120 with a height about 3 m). In another embodiment (not shown), theshield 240, 240 a forms an integral part of an outlet end 190 of theouter wall of the plasma generator 110, 110 a. As the outlet end 190 ofthe generator 110, 110 a is inserted into the opening 185, 185 a, theouter wall of the generator 110, 110 a can protrude further within thecompression chamber 120 forming a vertical, annular, wall around theoutlet end 190. The shield 240, 240 a can be so shaped and dimensionednot to interfere with the cavity formation and/or cavity generationsystem and can be tuned to fit a specific geometry of the compressionchamber 120. The walls of the shield 240, 240 a can be parallel to theaxis 250 or can be slightly angled with respect to the axis 250.

In another embodiment and referring to FIG. 3, a liquid jet controldevice is configured to direct a jet deflector 300 in the form of aplurality of solid state pellets 300 (“solid pellet jet deflector”) atthe liquid state fluid jet (“liquid fluid jet”) 180. The means forinjecting is a pellet driver 320 such as a rail gun as shown in FIG. 3;however, other pellet drivers can be provided such as a compressed gasgun. The rail gun is positioned inside the plasma generator 110 andfaces downwards into the chamber 140 along an axis 350 wherein thecavity 140 is expected to form.

Instead of a pellet driver, the means for injecting can be a passivepellet injector in the form of a downwardly facing conduit with acontrollable gate (not shown) at a discharge end of the conduit. Theconduit is sized to store a single line of pellets, and the gate can beopened to allow the pellets 300 to be discharged into the cavity 140.The pellet injector can be used when there is a sufficient negativepressure differential between the jet control device 110 and the chamber120 to extract the pellets 300 (with the assistance of gravity) from theconduit and into the cavity 140 such that the pellets achieve sufficientvelocity to disrupt or deflect a liquid jet 180 emerging from the liquidjet formation location.

The jet control device further includes a pellet container 310 storingthe pellets 300 and having a loading mechanism for delivering thepellets to the pellet driver 320. The container 310 comprises an inlet(not shown) through which a refill of additional pellets can be providedand an outlet through which a controlled release of a pellet from thecontainer 310 into the pellet driver 320 can be made. The loadingmechanism can be a conveyor belt which loads the pellets 300 into abreach of the rail gun 320; the rail gun 320 can be operator to fire thepellets 300 in a relatively rapid sequence along the axis 350. In somecases, a brief time period can be provided (1-2 s) to allow for loadingof the next cartridge of pellets 300.

One or more pellets 300 can be injected into the cavity 140 in order tointercept and collide with a central liquid jet 180 that can begenerated upon collapse of the cavity 140. For example, the pellets 300can be injected so that they move along the axis 250 to intercept thejet 180. The pellets 30 are sized to counteract the momentum of theemerging jet 180 at the collapse point. Flow velocities in the pellets300 can range from a few tens m/s to a few hundreds of m/s, depending onthe implementation and operating conditions. For example, for a fluidjet with a momentum P=υ×m at the collapse point of about 20-160 kg m/sand a lead pellet with mass of about 0.08 kg (cube of 2 cm) to 0.64 kg(cube of 4 cm) the velocity of the pellets 300 is about 30-2000 m/s. Thepellets 300 can be sized and shaped accordingly not to interfere withthe plasma entering the cavity 140 or to disturb the cavity 140 itself(for example, the size of the pellet can be around ⅕ to 1/10 of thediameter of the cavity 140). Each pellet 300 is configured to collidewith and deflect the high speed jet 180 dispersing it into a pluralityof smaller jets. In particular, each pellet 300 has a face surface 301sized and shaped to deflect an initial direction of the high speed jet180 to a desired new direction. For example, the pellet 300 can have aconcave or a cone-shaped face surface 301. Each pellet 300 can be madeof the same material as the liquid medium in the chamber 120 and canhave various different shapes such as for example, spherical,ellipsoidal, cylindrical, rectangular, or any other suitable shape.

The jet control device may further include a timing system (not shown)configured to coordinate the release and the injection of the pellet 300with the cavity collapse and formation of liquid jet 180. In oneimplementation a single pellet 300 can be injected to intercept andredirect the liquid jet 180. In another implementation, an array ofpellets 300 can be injected in the cavity 140. The liquid jet 180 may beintercepted by the one or more of the pellets 300. When the pellets areof the same composition of the liquid medium, part of the liquid mediumin the chamber 120 is extracted for manufacturing new pellets 300 (meansfor manufacturing the pellets not shown).

The jet control device can further include a liquid blob shield such asa constriction 330 that is formed in proximity to the annular opening185 of the chamber 120. The constriction 330 can be configured so toallow the plasma to pass over the constriction 330 but to prevent theliquid blob, formed when the pressure wave 170 approaches the outlet end190, to enter into the plasma generator 110. The constriction 330 canact as a lip formed at the entrance (outlet end 190) of the generator110. It can protrude slightly downwardly toward the inside of thechamber 120 and can be configured to be an integral part of the chamber120 or of the outer wall of the generator 110. In addition, theconstriction 330 can at least partially prevent the jet 180 fromentering the plasma propagation channel and thus can act as a shieldand/or a deflector with respect to the jet 180 as well. In someimplementations, both the constriction 330 and the shield 240 can beused to prevent the blob of liquid material entering the generator(s)110, 110 a.

Simulations of the cavity collapse and subsequent formation of the fluidjets have been carried out using the computational fluid dynamics (CFD)code OpenFOAM (available from the OpenFOAM Foundation, Winnersh, UnitedKingdom) and finite element analysis (FEA) code LS-DYNA (available fromLivermore Software Technology Corporation, Livermore, Calif.). Exampleresults of the simulations are illustrated in FIGS. 4-9.

A CFD simulation of a cylindrical plasma compression system having aradius of 1.5 m and height of 2 m was carried out using cylindricalgeometry. The radius of the cavity was set to be 0.2 m and the cavitywas set to extend over the entire height of the cylinder. Simulationswere carried out by using a molten metal such as a molten lead ormixture of molten lead and lithium as an example of the fluid. Soundspeed in the fluid (e.g., lead) was taken as 1800 m/s. Simulations werecarried out for three different amplitudes of a pressure pulse:

-   -   1. P=1.5×10¹⁰ Pa, which corresponds to the pressure amplitude in        one prototype plasma compression chamber near the cavity        interface in the case of a spherically converging wave;

-   2. P=2×10⁹ Pa, which corresponds to an initial pressure amplitude in    a small size compression chamber and for a piston velocity of about    50 m/s;    -   3. P=5×10⁸ Pa, which corresponds to the pressure amplitude in        the small size compression chamber for a piston velocity of        about 15 m/s.

FIGS. 4 and 5 illustrate vertical and horizontal cross-sections of theCFD computational model for a pressure pulse with an amplitude ofP=1.5×10¹⁰ Pa (the cross-sections look generally similar for the otherpressure pulse amplitudes). The curved section 410 (FIGS. 4 and 5) showsa pressure pulse at early stages of propagation. Solid, vertical blacklines 420 of FIG. 4 and circular-shaped curve 420 of FIG. 5 show aninitial fluid/gas interface of the cavity 140 in a vertical direction(FIG. 4) and in a horizontal direction (FIG. 5), respectively.

For a pulse with 1.5×10¹⁰ Pa, particle velocity is around 800 m/s (forlead as fluid) calculated by the following equation (1).V _(particle) =P/(ρ×c)  (1)

where P is a pressure of a pulse, ρ is the density of the fluid and c isthe speed of sound in the fluid.

A shape of the collapse of the cavity depends at least partly on apressure distribution along the cavity interface at a time when thepressure pulse hits the interface. The initial velocity of the interfaceis proportional to the particle velocity of the pressure pulse which inturn is proportional to the pressure at the time the pressure pulsereaches the interface. As showed in FIGS. 4 and 5, the pressure pulse410 has a spherical shape so the pulse in the central part of thechamber (e.g., along a midline or equator of the cylindrical chambershown in FIG. 4) may reach the cavity interface first. Away from themidline, the pressure pulse will arrive at the cavity interface after atime delay. Therefore, the arrival of pressure pulse along the length ofthe cavity will occur over a time interval. For a high amplitudepressure pulse (e.g., P=1.5×10¹⁰ Pa), the interface velocity (Vinterface=2×V_(particle)) in the fluid can be of the order of magnitudeas the speed of sound in the fluid based on the linear relation. Forexample, an interface velocity in lead is around approximately 1600 m/swhich is close to the speed of sound in the lead approximately 1800 m/s.In this example, the time delay of the arrival of the pressure pulsealong the length of the cavity interface may be relatively large so thata pinch collapse of the cavity occurs in the center of the chamber. Fora low amplitude pulse, the interface velocity can be much slower thanthe speed of sound in the fluid so that the time delay of the pressurepulse arrival along the length of the cavity becomes negligible,resulting in a more uniform collapse along the length of the cavityinterface (as compared to a high amplitude pressure pulse). Thenumerical simulations show that regardless of the shape of the cavitycollapse (e.g., pinch collapse or more uniform collapse of the cavityinterface), such cavity collapse results in generation of a high speedcentral jet and a liquid blob (see the example shown in FIG. 7 a).

The FEA code was used to model the piston system, the fluid (e.g., lead)and the vacuum/air in a elliptical plasma compression vessel. Themodeling was done for a 2-dimensional axisymmetric geometry. FIG. 6illustrates an example of the simulated model. The interior 610 of theelliptical vessel is filled partially with fluid (e.g., lead orlead/lithium mixture). The cavity is shown by reference sign 620, andthe pistons are shown by reference sign 630. The inner radius of thevessel is 2 m and the outer radius is 2.3 m. The pistons accelerate witha velocity of approximately 40 m/s and strike a wall of the sphere andsubsequently strike the fluid in the vessel. The reference numeral 640indicates a central shaft inserted in the center of the cavity tocorrespond to the jet deflector 12 (FIGS. 1A, 1B) or deflector 210 (FIG.2).

Results of both CFD and FEA simulations have shown that jets emerging asa result of the cavity collapse can be divided into (i) a high speedcentral jet generated by the actual collapse at the axis of the cavity(e.g., a singular collapse point) and (ii) a blob of fluid, e.g., a massof fluid dribbling into the injector's nozzle when the pressure pulsewavefront approaches the generator's outlet end. In the simulationsperformed, the blob is observed for all amplitudes of a pressure pulseand the speed of the blob is much slower than that of the high speedcentral jet. FIGS. 8 a and 8 b show examples of the velocity of the highspeed jet and the liquid blob, respectively. As illustrated in FIG. 8 athe central jet 720 can emerge at a speed of several kilometers persecond whereas the blob 710 can emerge at tens of meters per second(FIG. 8 b). The examples of the simulations of FIGS. 8 a and 8 b showthat the velocity of the central jet 720 can be in a range fromapproximately 1500 m/s to approximately 2500 m/s while the velocity ofthe blob 710 can be in a range from approximately 50 m/s toapproximately 75 m/s, which is only about 3% of the central jet'svelocity.

A comparison of the fluid jet with and without the central shaft 640 isshown in FIGS. 7 and 9. FIGS. 7 a and 9 a show formation of the highspeed central jet, such as a thin filament of fluid 720 when a deflector(shaft 640) is not present in the cavity. FIG. 7 a further showsformation of the blob 710 near the opening of the chamber. The jet 720can be a high speed jet that flows along the axis of the cavity. Inorder to eliminate or reduce the central jet, a simulation was carriedout with a shaft 640 inserted in the center of the cavity (see FIGS. 7b, 9 b). FIGS. 7 b and 9 b show the plurality of dispersed jets 730formed when the shaft 640 is inserted into the cavity. Simulations haveshown that when the central shaft is present in the cavity, theformation of the central high speed jet can be avoided and jets 730formed by the collapse of the cavity at the surface of the shaft 640tend to be deflected to hit the main body of the fluid. Furthermore,according to the simulations, the size of the jets 730 formed when theshaft is present is approximately one-quarter the size of the jet 720formed when no shaft is present. In the example shown in FIG. 7 b, thepresence of the shaft 640 did not completely eliminate the fluid blob710, although it did reduced its size.

FIG. 9 a illustrates a velocity of the jet formed when no central shaft640 is present in the cavity while FIG. 9 b illustrates a velocity ofthe jets formed when the central shaft 640 is inserted into the cavity.The simulations have shown that when the shaft is present in the cavitythe velocity of the jets 730 can be reduced to approximately 60% of thevelocity of the jet 720, when the shaft 640 is absent from the cavity.

A geometrical shield corresponding to the shield 240 of FIG. 2 has alsobeen simulated. The simulation has shown that the use of the shield canreduce the likelihood and can prevent the blob of fluid from enteringthe generator. The vertical length of the shield depends of the size ofthe chamber and in the example simulated the vertical length was takento be around 0.25 m. This is only for the purpose of illustration anddifferent dimensions of the shield can be used in other implementations.

While particular elements, embodiments and applications of the presentdisclosure have been shown and described, it will be understood, thatthe scope of the disclosure is not limited thereto, since modificationscan be made by those skilled in the art without departing from the scopeof the present disclosure, particularly in light of the foregoingteachings. Thus, for example, in any method or process disclosed herein,the acts or operations making up the method/process may be performed inany suitable sequence and are not necessarily limited to any particulardisclosed sequence. Elements and components can be configured orarranged differently, combined, and/or eliminated in variousembodiments. The various features and processes described above may beused independently of one another, or may be combined in various ways.All possible combinations and subcombinations are intended to fallwithin the scope of this disclosure. Reference throughout thisdisclosure to “some embodiments,” “an embodiment,” or the like, meansthat a particular feature, structure, step, process, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. Thus, appearances of the phrases “in some embodiments,” “inan embodiment,” or the like, throughout this disclosure are notnecessarily all referring to the same embodiment and may refer to one ormore of the same or different embodiments. Indeed, the novel methods andsystems described herein may be embodied in a variety of other forms;furthermore, various omissions, additions, substitutions, equivalents,rearrangements, and changes in the form of the embodiments describedherein may be made without departing from the spirit of the inventionsdescribed herein.

Various aspects and advantages of the embodiments have been describedwhere appropriate. It is to be understood that not necessarily all suchaspects or advantages may be achieved in accordance with any particularembodiment. Thus, for example, it should be recognized that the variousembodiments may be carried out in a manner that achieves or optimizesone advantage or group of advantages as taught herein withoutnecessarily achieving other aspects or advantages as may be taught orsuggested herein.

Conditional language used herein, such as, among others, “can,” “could,”“might,” “may,” “e.g.,” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orsteps. Thus, such conditional language is not generally intended toimply that features, elements and/or steps are in any way required forone or more embodiments or that one or more embodiments necessarilyinclude logic for deciding, with or without operator input or prompting,whether these features, elements and/or steps are included or are to beperformed in any particular embodiment. No single feature or group offeatures is required for or indispensable to any particular embodiment.The terms “comprising,” “including,” “having,” and the like aresynonymous and are used inclusively, in an open-ended fashion, and donot exclude additional elements, features, acts, operations, and soforth. Also, the term “or” is used in its inclusive sense (and not inits exclusive sense) so that when used, for example, to connect a listof elements, the term “or” means one, some, or all of the elements inthe list.

The example calculations, simulations, results, graphs, values, andparameters of the embodiments described herein are intended toillustrate and not to limit the disclosed embodiments. Other embodimentscan be configured and/or operated differently than the illustrativeexamples described herein.

The invention claimed is:
 1. A plasma compressing system, the systemcomprising: a plasma generator configured to generate plasma and havinga discharge outlet for discharging the generated plasma; a plasmacompression chamber having an outside wall defining an inner cavity ofthe chamber and having an opening, the inner cavity of the chamber beingpartially filled with a liquid medium, the discharge outlet of theplasma generator being in fluid communication with the inner cavity ofthe compression chamber via the opening, such that the generated plasmacan be discharged into the plasma compression chamber; a pressure wavegenerator comprising a plurality of pistons arranged around the chamber,the pistons being configured to generate a converging pressure wave intothe liquid medium; a cavity generating means for generating an elongatedempty cavity into the liquid medium, the cavity having a first end and asecond end, the first end being aligned at least partially with thedischarge outlet of the plasma generator such that the plasma dischargedby the plasma generator enters the elongated cavity, and wherein theconverging pressure wave reaching a cavity interface collapses thecavity enveloping the plasma; and a jet control device comprising: meansfor injecting a jet deflector material in communication with a jetdeflector material source and having a discharge end directed at a jetformation location in the cavity, the means for injecting configured toinject the jet deflector material into the cavity such that a fluid jetformed at the jet formation location is disrupted or deflected away fromthe plasma generator.
 2. The plasma compressing system of claim 1,wherein the jet deflector material is in a liquid state, the means forinjecting is a liquid injector comprising a liquid conduit with aninjection nozzle at the discharge end.
 3. The plasma compressing systemof claim 2, wherein the means for injecting further comprises a controlvalve for controlling the flow of the liquid jet deflector out of thenozzle.
 4. The plasma compressing system of claim 2, wherein theinjector further comprises pressurization means coupled to the conduitand configured to supply sufficient pressure to direct a continuousstream of the liquid jet deflector material to the jet formationlocation, the stream having a substantially uniform radius.
 5. Theplasma compressing system as claimed in claim 4 wherein thepressurization means is selected from a group consisting of a pump and apressurized gas source.
 6. The plasma compressing system as claimed inclaim 1, wherein the jet deflector is in a solid state, the means forinjecting is an extruder comprising a die and a ram configured toextrude the jet deflector material out of the extruder in the form of anelongated rod.
 7. The plasma compressing system as claimed in claim 6wherein the extruder is further configured to extrude the jet deflectormaterial in the form of an elongated rod having a length that extends atleast from the discharge end of the extruder to the jet formationlocation.
 8. The plasma compressing system as claimed in claim 1 whereinthe jet deflector is in a solid state in the form of discrete pellets,and the means for injecting is a pellet driver having a breach and amovable gate for controlling the injection of at least one solid statejet deflector pellet at the jet formation location.
 9. The plasmacompressing system as claimed in claim 8 wherein the pellet driver isselected from a group consisting of a rail gun and a compressed gas gun.10. The plasma compressing system of claim 8, wherein each pellet has aface surface with a concave shape.
 11. The plasma compressing system asclaimed in claim 6 wherein the elongated solid rod has dimensions thatcause the collapse of the cavity to occur at a surface of the elongatedsolid rod.
 12. The plasma compressing system of claim 1 furthercomprising a shield disposed in vicinity of the opening of the plasmacompression chamber, and having an annular configuration for inhibitinga blob of liquid medium from escaping the plasma compression chamber andentering the plasma generator.
 13. The plasma compression device ofclaim 12, wherein the shield is a wall projecting downwardly into theinner cavity of the chamber surrounding the opening.
 14. The plasmacompression device of claim 12, wherein the shield is a lip shapedconstriction formed at an edge of the opening and projecting radiallytoward a center of the cavity.
 15. The plasma compressing system asclaimed in claim 1 wherein the jet deflector material has the samecomposition as the liquid medium and the system further comprises aliquid medium collection tank in fluid communication with the chamberand a fluid conduit fluidly coupling the collection tank with the jetdeflector material source.
 16. The plasma compressing system as claimedin claim 8 further comprising a controller programmed to control atiming of the injection of the at least one solid state jet deflectorpellet into the cavity such that the pellet is in proximity to thecollapse point when the cavity collapses.
 17. The plasma compressingsystem as claimed in claim 2 further comprising a controller programmedto control a timing of the injection of the continuous liquid stream ofjet deflector material into the cavity such that the cavity collapses atthe surface of the continuous liquid stream.